In a fixing device of an electrophotographic printer, when a temperature of a heating member of the fixing device is increased to a fixing temperature after a printing command is received, the temperature rise may be slower at both end portions of the heating member than at a central portion of the heating member. In this case, it is necessary to wait for printing start until the temperature of the end portions of the heating member becomes sufficiently high, specifically, the temperature of the end portions reaches a predetermined printing start temperature.
Regarding the above problem, in the related art, when a pixel density at an end portion of the sheet is equal to or smaller than a predetermined value, the printing starts even though the temperature of the end portions of the heating member is lower than a normal printing start temperature (refer to JP-A-2006-11120). Specifically, according to this technology, when the pixel density at an end portion of the sheet is equal to or smaller than the predetermined value, the printer waits until the temperature of the end portions of the heating member reaches a predetermined temperature lower than the printing start temperature and starts printing when the temperature reaches the predetermined temperature.
Also, in order to increase a printing speed, a feeding timing of the sheet is accelerated such that a time when the temperature of the heating member reaches a fixing temperature and a time when an image region on the sheet reaches the heating member are to be the same (refer to JP-A-2010-271410).
However, according to the technology disclosed in JP-A-2006-11120, since the timing of the printing start, i.e., the feeding timing of the sheet is decided on the basis of the temperature of the end portions of the heating member, the control is complicated.
Also, the heat may not be sufficiently accumulated in the heating member of the fixing device at the time that a printing starts and a first sheet reaches the heating member. In this case, the heat of the heating member is deprived at a head part of the sheet in a conveying direction, so that the temperature of the heating member is lowered and a fixing defect may be thus caused at a rear part of the sheet in the conveying direction. For this reason, when the heat has not been sufficiently accumulated in the heating member, the sheet feeding should start after the heat is sufficiently accumulated in the heating member. As a result, it is not possible to rapidly perform the printing.